Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Busulfan (Bu) resistance is a major obstacle to hematopoietic stem cell transplantation (HSCT) of patients with chronic or acute myelogenous leukemia (CML or AML). We used gene expression analysis to identify cellular factors underlying Bu resistance. Two Bu-resistant leukemia cell lines were established, characterized and analyzed for differentially expressed genes. The CML B5/Bu250(6) cells are 4.5-fold more resistant to Bu than their parental B5 cells. The AML KBM3/Bu250(6) cells are 4.0-fold more Bu-resistant than KBM3 parental cells. Both resistant sublines evade Bu-mediated G2-arrest and apoptosis with altered regulations of CHK2 and CDC2 proteins, constitutively up-regulated anti-apoptotic genes (BCL-X(L), BCL2, BCL2L10, BAG3 and IAP2/BIRC3) and down-regulated pro-apoptotic genes (BIK, BNIP3, and LTBR). Bu-induced apoptosis is partly mediated by activation of caspases; use of the inhibitor Z-VAD-FMK completely abrogated PARP1 cleavage and reduced apoptosis by approximately 50%. Furthermore, Bu resistance in these cells may be attributed in part to up-regulation of HSP90 protein and activation of STAT3. The inhibition of HSP90 with geldanamycin attenuated phosphorylated STAT3 and made B5/Bu250(6) and KBM3/Bu250(6) more Bu-sensitive. The analysis of cells derived from patients classified as either clinically resistant or sensitive to high-dose Bu-based chemotherapy indicated alterations in gene expression that were analogous to those observed in the in vitro model cell lines, confirming the potential clinical relevance of this model for Bu resistance.
 ...
PMID:Altered gene expression in busulfan-resistant human myeloid leukemia. 1833 23

5-Fluorouracil (5-FU) is an important chemotherapeutic agent for nasopharyngeal carcinoma (NPC). However, drug resistance may occur after several cycles of 5-FU-based chemotherapy. The oncogene B-cell-specific Moloney murine leukemia virus insertion site 1 (BMI-1) has been shown to be involved in the protection of cancer cells from apoptosis. In this study, 5-FU treatment could increase the percentage of apoptotic NPC cells among BMI-1/RNAi-transfected cells than that among cells transfected with the empty vector. The 50% inhibitory concentration (IC(50)) values of 5-FU were significantly decreased to a greater extent in the cells transfected with BMI-1/RNAi. Most importantly, the expression of phospho-AKT and the anti-apoptotic protein BCL-2 were downregulated in the cells in which BMI-1 expression was inhibited, whereas the apoptosis-inducer BAX was observed to be upregulated. Abrogation of AKT pathway by a PI3K inhibitor could not further increase the sensitivity to 5-FU in the cells with reduced BMI-1 expression. Taken together, BMI-1 depletion enhanced the chemosensitivity of NPC cells by inducing apoptosis; which is associated with inhibition of the PI3K/AKT pathway.
 ...
PMID:Downregulation of BMI-1 enhances 5-fluorouracil-induced apoptosis in nasopharyngeal carcinoma cells. 1845 7

Differential scanning calorimetry (DSC) and complementary techniques were utilized to evaluate the sensitivity of B-cell chronic lymphocytic leukemia (B-CLL) cell samples in vitro exposed to cladribine or fludarabine in combination with mafosfamide. Mafosfamide, the active in vitro form of cyclophosphamide with both purine analogs produced the cytotoxic effect on mononuclear cell probes, however, to a different degree. Our results indicated that higher sensitivity of examined leukemic cell samples to the used drug combinations was usually accompanied by a marked decrease or even a complete loss of thermal transition at 95+/-3 degrees C in DSC scans of nuclear preparations as well as by more significant reduction of cell viability, higher extent of DNA damage estimated by the comet assay and by dropping/disappearance of anti-apoptotic protein Mcl-1 in comparison with untreated cells. We have also observed that the reduction of transition at 95+/-3 degrees C in thermal scans of nuclear preparations isolated from blood of B-CLL randomized patients who showed response to cladribine or fludarabine combined with cyclophosphamide, i.e., CC and FC, respectively, corresponded with the decrease or disappearance of anti-apoptotic proteins Bcl-2 and/or Mcl 1. In conclusion, these in vitro and in vivo studies revealed that quick DSC technique, usually supplemented by other methods, is a potent tool to distinguish efficacy of B-CLL treatment and could be helpful in choosing the most effective manner of treatment for this type of leukemia.
 ...
PMID:Calorimetric study as a potential test for choosing treatment of B-cell chronic lymphocytic leukemia. 1867 14

A major issue in the treatment of leukemia is resistance to chemotherapeutic drugs. The most common mechanism encountered in the laboratory is the increased efflux of hydrophobic cytotoxic drugs that is mediated by a family of energy-dependent transporters. Besides, resistance to apoptosis can also cause failure in the treatment of leukemia. Recently, we have introduced 4-(4-bromophenyl)-2,3-dihydro-N,3-bis(3,4,5-trimethoxyphenyl)-2-oxoidmidazole-1-carboxamide (MZ3) as a novel synthesized combretastatin A-4 analogue which is a potent and specific compound against leukemia cells both in vitro and in vivo. Aim of this study was to evaluate the effect of MZ3 on multidrug-resistant (MDR) cancer cells of leukemia, and explore the antimultidrug-resistant mechanisms. Here, we observed that the MDR leukemia cell models investigated, overexpressing MDR1 (P-gp), were hypersensitive against MZ3. Parental K562, HL60 cells and MDR1-overexpressing K562R, HL60R cells were employed in this study. MZ3 hypersensitivity was confirmed to be based on great apoptosis induction and cell cycle arrest at unaltered intracellular drug accumulation. Cell proliferation assay demonstrated that, compared with HL60 and K562 cells, HL60R and K562R cells exhibited 1.3-fold and 2.4-fold resistance to MZ3, showing 26.9-fold and 92.2-fold resistance to daunorubicin (DNR) respectively. Moreover, real-time RT-PCR result showed that MZ3 impacted the transcription of MDR1 gene and western blotting results indicated that MZ3 can activate apoptosis on MDR cells by downregulating the anti-apoptotic protein XIAP levels and inducing the decrease in the phosphorylation state of ERK. Summarizing, our data demonstrate that MZ3 can inhibit the MDR function of leukemia cells, and it exerts the effect through altering the transcription of MDR1 genes and downregulating the anti-apopotic protein levels. MZ3 may be a potential candidate for further research and development in anti-MDR territory.
 ...
PMID:Antimultidrug-resistant effect and mechanism of a novel CA-4 analogue MZ3 on leukemia cells. 1871 89

The protein kinase Syk is a key mediator of proximal B-cell receptor (BCR) signaling. Following antigen stimulation, Syk is recruited to the BCR and becomes activated by phosphorylation at Y352. Recently, Syk was found to be constitutively phosphorylated in several common B-cell lymphoma subtypes, indicating a role for antigen-independent Syk activation in the pathogenesis of these diseases. We now report that Syk is constitutively phosphorylated on the activating Y352 residue in chronic lymphocytic leukemia (CLL) B cells. To examine the effects of constitutive Syk activity on intracellular signaling and leukemic cell survival, we performed in vitro studies with the Syk inhibitor R406. Treatment with R406 induced leukemic cell apoptosis in the majority of investigated cases and affected the basal activity or expression of several pro-survival molecules regulated by Syk, including the Akt and extracellular signal-regulated (ERK) kinases, and the anti-apoptotic protein Mcl-1. In addition, R406 prevented the increase in leukemic cell viability induced by sustained BCR engagement and inhibited BCR-induced Akt activation and Mcl-1 upregulation. Collectively, these data identify Syk as a potential target for CLL treatment and suggest that inhibition of this kinase could provide a double therapeutic benefit by disrupting both antigen-dependent and antigen-independent signaling pathways that regulate leukemic cell survival.
Leukemia 2009 Apr
PMID:Inhibition of constitutive and BCR-induced Syk activation downregulates Mcl-1 and induces apoptosis in chronic lymphocytic leukemia B cells. 1909 49

Signals that control the fine balance between cell death and cell survival are altered during tumorigenesis. Understanding the mechanisms by which this balance is perturbed, leading to excessive cell survival, is important for designing effective therapies. Proteins belonging to the B-cell lymphoma (BCL) family are known to regulate death responses to apoptotic signals, especially those originating within cells. A subset of BCL family members capable of inhibiting cell death is known to contribute to tumorigenesis; however, it is not known whether all six antiapoptotic BCL family members play a causal role in tumor development. Using a mouse model of MYC-driven leukemia, we showed that, in addition to the well characterized BCL2 and BCLxl (BCL2L1), the other four family members -- BCLw (BCL2L2), BCLb (BCL2L10), BFL1 (BCL2A1) and MCL1 -- also cooperate with MYC to accelerate leukemogenesis. In addition, high levels of each family member are found in either solid human tumors or cell lines derived from human leukemias or lymphomas.
 ...
PMID:MYC-induced myeloid leukemogenesis is accelerated by all six members of the antiapoptotic BCL family. 1913 12

Tanshinone IIA, a diterpene quinone extracted from the traditional herbal medicine, Salvia miltiorrhiza Bunge, has been reported to have anti-tumor effects on a large variety of cancer cells. The present study was undertaken to investigate the in vitro antiproliferation and apoptosis inducing effects of Tanshinone IIA on leukemia THP-1 cell lines and its mechanisms of action. MTT assay was used to detect the cell growth inhibitory rate; cell apoptotic rate and the mitochondrial membrane potential (Deltapsim) were investigated by flow cytometry (FCM), apoptotic morphology was observed by Hoechst 33258 staining and DNA fragmentation analysis. The expression of caspase-3 and different apoptosis modulators were analyzed by Western blotting. The results revealed that Tanshinone IIA inhibited the growth of THP-1 cells and caused significant apoptosis, the suppression was both in time- and dose-dependent manner. After treatment by Tanshinone IIA for 48 h, the percentage of disruption of Deltapsim gradually increased in a dose-dependent manner along with marked changes of cell apoptosis. Western blotting showed cleavage of the caspase-3 zymogen protein (32-kDa) with the appearance of its 20-kDa subunit and a dose-dependent cleavage of PARP, with the appearance of 89-kDa fragment; The expression of Bcl-2 and survivin was down-regulated remarkably while Bax expression was up-regulated concurrently after the cells were treated with Tanshinone IIA for 48 h. We therefore conclude that Tanshinone IIA has significant growth inhibition effects on THP-1 cells by induction of apoptosis, and that Tanshinone IIA-induced apoptosis on THP-1 cells is mainly related to the disruption of Deltapsim and activation of caspase-3 as well as down-regulation of anti-apoptotic protein Bcl-2, survivin and up-regulation of pro-apoptotic protein Bax. The results indicate that Tanshinone IIA may serve as a potential anti-leukemia reagent.
 ...
PMID:Tanshinone IIA inhibits leukemia THP-1 cell growth by induction of apoptosis. 1928 11

Myeloid cell leukemia-1 (Mcl-1, Mcl-1L) is an anti-apoptotic protein of the Bcl-2 family that acts as a critical molecule in apoptosis control. Mcl-1 pre-mRNA can undergo alternative splicing to yield the short isoform, Mcl-1S, which resembles BH3-only pro-apoptotic proteins and induces apoptosis. Overexpression of Mcl-1 may play a role in various human tumors, and Mcl-1 may serve as a target in cancer therapy. In this study, we found an imbalance between the expression levels of Mcl-1L and Mcl-1S in the skin basal cell carcinoma (BCC) cell line when compared with primary keratinocytes. We showed that overexpression of Mcl-1S induces apoptosis in BCC cells. Finally, we showed that Mcl-1 antisense morpholino oligonucleotides (AMOs) can specifically target Mcl-1 pre-mRNA and shift the splicing pattern from Mcl-1L to Mcl-1S mRNA and protein. This shift increases the level of pro-apoptotic Mcl-1S and reduces the level of anti-apoptotic Mcl-1L, which induces apoptosis in BCC cells and AGS cells, a human gastric adenocarcinoma epithelial cell line. Thus, this report provides a strategy for cancer therapy in which AMOs change the alternative splicing pattern of Mcl-1 pre-mRNA and thereby induce apoptosis.
 ...
PMID:Modification of alternative splicing of Mcl-1 pre-mRNA using antisense morpholino oligonucleotides induces apoptosis in basal cell carcinoma cells. 1936 67

Myeloid cell leukemia-1 (Mcl-1) is an anti-apoptotic protein that is regulated by the constitutive androstane receptor (CAR). Activation of CAR can protect the liver against bile acid-induced toxicity and it may have a role in cell death via apoptosis by altering expression of Bcl-2 family proteins such as myeloid cell leukemia-1 (Mcl-1). Our aim was to determine if activation of CAR reduces hepatocellular apoptosis during cholestasis as a mechanism of hepatoprotection. CAR(+/+) (WT) and CAR(-/-) (CAR-null) mice were pre-treated with compounds known to activate CAR prior to induction of intrahepatic cholestasis using the secondary bile acid lithocholic acid (LCA). Pre-treatment with the CAR activators phenobarbital (PB) and TCPOBOP (TC), as well as the non-CAR activator pregnenolone 16alpha-carbontrile (PCN), protected against LCA-induced liver injury in WT mice, whereas liver injury was more extensive without CAR (CAR-null). Unexpectedly, expression of anti-apoptotic Mcl-1 and Bcl-x(L) was not increased in hepatoprotected mice. Compared to unprotected groups, apoptosis was decreased in hepatoprotected mice as evidenced by the absence of cleaved caspase 3 (cCasp3). In contrast to the cytoplasmic localization in the injured livers (LCA and oltipraz), Mcl-1 protein was localized in the nucleus of hepatoprotected livers to potentially promote cell survival. This study demonstrates that although apoptosis is reduced in hepatoprotected mice pre-treated with CAR and non-CAR activators; hepatoprotection is not directly a result of CAR-induced Mcl-1 expression.
 ...
PMID:Decreased apoptosis during CAR-mediated hepatoprotection against lithocholic acid-induced liver injury in mice. 1943 68

This study investigates the ability of a synthetic PPAR-gamma agonist, rosiglitazone (RGZ), to induce apoptosis in leukemia K562 cells. The results revealed that RGZ (>40 mmol/L) inhibits the growth of K562 cells and causes apoptosis in a time and dose-dependent manner. Apoptosis is observed clearly by Hoechst 33258 staining. Western blotting analysis demonstrates the cleavage of caspase-3 zymogen protein with the appearance of its 17-kD subunit and a dose-dependent cleavage of poly (ADP-ribose) polymerase. Furthermore, RGZ treatment down-regulates anti-apoptotic protein Bcl-2 and up-regulates pro-apoptotic protein Bax in a dosedependent manner after the cells are treated for 48 hours. Telomerase activity is decreased concurrently in a dosedependent manner. We therefore conclude that RGZ induces apoptosis in K562 cells in vitro, and that RGZ-induced apoptosis in K562 cells is highly correlated with activation of caspase-3, decreasing telomerase activity, down-regulation of the anti-apoptotic protein Bcl-2, and up-regulation of the pro-apoptotic protein Bax.
 ...
PMID:Peroxisome proliferator-activated receptor-gamma agonist rosiglitazone--induced apoptosis in leukemia k562 cells and its mechanisms of action. 1948 36


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>